Initialization of class variables during migration

Hi all-

Perhaps this is not a best practice, but we currently have class
variables in several class that are initialized by calls to AR
classes. For example:

   class Foo < ActiveRecord::Base
     @@my_class_var = Bar.find(:first)
   end

When using migrations to set-up a new environment, this fails as the
'bars' table does not yet exist when the environment is loaded. Any
thoughts on how to work through this? I imagine this is fairly
common, but like I said maybe this is not a best practice.

Thanks,
Josh